The present disclosure relates to monitoring machinery or other apparatus during operation, and more specifically, to systems used to detect fault frequency sets for components to enable failing components to be identified.
Some machines, such as machines incorporating rotating elements, often include bearings or other components, which, due to the heavy use and operating conditions of the machines, are often replaced during normal operation of the machines. During maintenance servicing, bearings from one vendor are often replaced with bearings from a different vendor. Thus, after maintenance sessions, similar or identically-configured bearings from more than one vendor may be in service in any particular machine. For example, complex rotating machinery, such as the gearbox of a wind-powered turbine, may incorporate numerous rolling elements or bearing sets. Typically, the bearing sets include at least two sets of rolling bearings and at least one thrust bearing. For each such rolling element, the manufacturer of the rotating machinery may have qualified a number of vendors to supply bearings for a single machine. Therefore, it may be common for a single machine to include bearings sourced from three or more vendors.
Accordingly, in order for a machine owner/operator to efficiently and promptly service and maintain a machine, the owner/operator must be able to detect when bearings or rotating elements are exhibiting failure characteristics, and be able to promptly identify the location of the failing components. Typically, sensors (for example, vibration accelerometers) gather data from a machine either continuously or at specified intervals. If the output of the various sensors is representative of excessive vibration amplitudes at predefined frequencies, at least one bearing in the machine may be failing.
Each bearing vendor designs bearings to meet particular load carrying and external dimensional requirements. Because the bearing design problem can be solved different ways, different vendors can produce functionally similar bearings with similar or different inner race, outer race, and element dimensions. Different race and element dimensions will produce a different set of bearing fault frequencies. Typically, a vibration fault frequency is expressed as a multiple of the rotational speed of the shaft or other rotating element associated with a specific bearing set. Vibration fault frequency modes are governed by the bearing geometry used by each respective vendor. Each bearing, regardless of its configuration, location in a machine, or vendor, exhibits vibrations in at least five (5) modes: cage; outer race ball pass (ORBP); inner race ball pass (IRBP), ball (or element) spin (BS); and twice (2×) ball (or element) spin (2× BS). The different vibration fault frequency modes can be identified based on the frequency ranges in which they occur. For a given bearing, fault or failure in one or more of such modes will be indicated by increased vibration amplitudes at predefined frequencies.
Previously, in order for a machine owner/operator to promptly respond to a detected fault/failure situation, the machine owner/operator had to maintain records specific to each bearing or rolling element in each machine, including its fault frequency, and location in the machine. Such records would require updating each time a bearing was replaced or when new bearings are added. However, maintaining such detailed records can be cumbersome, and may be prone to error.